TALLAHASSEE — Gary Kompothecras, parent to two autistic children, believes early-childhood vaccines containing ethyl mercury are to blame for their condition. Other parents of autistic children share his belief.

But Kompothecras, a millionaire chiropractor best known for his "1-800-ASK-GARY" lawyer-medical referral service, is not just any parent. He is a major political donor whose connections and influence are helping him push controversial legislation that would change childhood vaccination requirements.

Critics say the proposal would endanger vaccine supplies in Florida and expose too many young children to preventable diseases and illnesses. But bill sponsors say they are just trying to give parents more choice and oversight in their children's health care.

The proposal went before its final Senate committee stop Tuesday, where senators tweaked the bill to appease some medical groups. But lawmakers ran out of time before voting, and the bill's fate is up in the air.

Bill sponsor Jeremy Ring hopes to get it sent right to the Senate floor for a vote, and the House can take up the measure after that. Or the Senate Ways and Means Committee could hear it again during one final meeting, yet to be scheduled. Committee Chairman J.D. Alexander said he'll take 24 hours to think about it.

"The biggest first say parents can get with their children is vaccinations," said Ring, D-Margate. "And right now they don't have enough of a say. They just go in and the doctor gives all these shots, boom, boom, boom."

A self-made millionaire, Kompothecras is a well-connected contributor and fundraiser to candidates, including Gov. Charlie Crist, Rep. Kevin Ambler, Senate President Jeff Atwater and Sen. Mike Bennett. In a recent interview with the Sarasota Herald-Tribune, Kompothecras called himself "the rainmaker."

Now he is using his position to push a vaccine bill that plenty of medical groups and health experts oppose.

SB 242 would give parents more authority to delay the pace at which their children are vaccinated against illnesses like measles, mumps and polio — as long as they are up to date with their shots by the time they enter the public school system. (Florida law already provides for exemptions from school vaccine requirements in the cases of religious beliefs or medical risks determined by a physician.)

The proposal, sponsored by Tampa Republican Rep. Kevin Ambler in the House, also would prohibit the use of vaccines for pregnant women and young children if the vaccines contain even a small percentage of ethyl mercury. Better known as thimerosal, it is used as a preservative in some vaccines, including flu and tetanus shots that are made in advance and in large quantities. Some people, including Kompothecras, believe thimerosal is the vaccine ingredient that makes their initially healthy children become autistic.

Kompothecras' son Bronson, 12, is severely autistic. Kompothecras blames "the nine vaccines he got in one day" at 18 months old. His daughter, Sarah Alice, 11, has a less severe form of autism.

The overwhelming opinion of doctors, including Judy Schaechter, an associate professor of pediatric medicine at the University of Miami, is that there is no "credible scientific link" between thimerosal and autism. Schaechter, in a lengthy letter to Sen. Nan Rich, a bill opponent, said the bill's limiting of thimerosal is unrealistic — well above levels approved by the FDA — and would prevent the use of flu vaccines.

Senators on Tuesday tweaked SB242 to appease powerful medical groups, including the Florida Medical Association, adding a provision that allows for the use of vaccines such as flu shots containing thimerosal if there is no readily available alternative.

Senators also added language to make clear that physicians who don't agree with a parent's desired vaccine schedule are not obligated to continue treating the child.

Kompothecras dismisses criticism from health officials.

"We're not against vaccines," he said Tuesday. "All I'm saying is, take the mercury out and don't give them nine shots at once."

He says pharmaceutical giants like Merck and Wyeth use donations to influence groups such as the American Academy of Pediatrics into supporting their profitable vaccines.

Kompothecras knows a thing or two about donations. In the 2008 general election, he donated a total of about $40,000 to individual candidates, including Ambler, Atwater, Bennett, and the Republican Party of Florida. And he gave more than $110,000 to the campaign for passage of Crist's property tax cut plan, Amendment 1.

Crist, a friend to Kompothecras, named him to the Governor's Autism Task Force last year. Crist did not take a stand this week on the legislation.

Staff writers Steve Bousquet, Alex Leary and Marc Caputo contributed to this report. Shannon Colavecchio can be reached at scolavecchio@sptimes.com or (850) 224-7263.